Electrical Help pls

maria_bettina wrote:
Hi! I bought a 250 Watt Electric Heater to stave off the chill at night (the tag says it uses 2.1A). We have solar panels to charge our 200A battery (I don't think that matters, but just in case).

Before the trip, I plugged the 250 Watt Heater into the 300 Watt inverter, and the inverter is plugged into the cigarette lighter in the camper. (The wire that runs from the cigarette lighter to the battery sized for 10A.) It worked fine. But now that my son and husband are on their trip, when they plug in the heater, the 10A fuse blows that is at the cigarette lighter. Twice.

They are able to play a DVD and TV by plugging it into the inverter. So everything works for the DVD and TV.

Nothing else is being charged or used on that inverter, nor at the cigarette lighter.

Note: There is an electric fridge/cooler, and it's being powered by the same auxiliary battery, but it's not on the same fuse (if that makes sense; I know I am not using the correct terminology).

My hubby just got to a campsite that has a power supply, and the heater works fine. So at least he is able to use it now without blowing fuses.

Any suggestions as to where we can start looking for the issue(s)?

TIA.

No worries, a common misconception.

Technical: P=I*E, 250W=2.1A*120VAC ok?

The 'problem' here is to get 250W AC out of a inverter it may require 300W on the +12V side of things. (%80 efficient) which equates to: 300W/12V=25A - thereby blowing the 10A fuse on the cigarette lighter.

So why did it work at home? (assuming at home you were plugged into shore power)

With the additional current provided by the campers onboard converter charger the battery voltage would be higher than what it would be by itself.

Consider if the battery voltage was 13.8V the current for 300W would be 21.7A and if the battery was @ 14.4V the current would be 20.8A.

Since many converter chargers are designed to actually charge the onboard battery, I'd suspect your voltage while plugged in was ether 13.8V or 14.4V.


- Mark0.